Starch hydrolysates, which include maltodextrins, glucose syrups and pure dextrose, are conventionally produced by the acidic and/or enzymatic hydrolysis of cereal or tuber starch. These hydrolysates contain a complex mixture of linear and branched saccharides and are, in fact, a mixture of glucose and glucose polymers, of extremely varied molecular weights. A first way of classifying them is the measurement of their reducing power, expressed conventionally by the concept of dextrose equivalent or D.E. By definition, a D.E. of 100 is assigned to pure glucose or dextrose, the monomer constituting these polymers. Starch, which is a very large glucose polymer, has a D.E. close to 0. A whole range of starch hydrolysates is found between these two values, the most hydrolysed having a D.E. close to 100 and the least hydrolysed having a D.E. which tends towards 0. Between both ranges, the maltodextrins have a dextrose equivalent (DE) of 1 to 20, and the glucose syrups have a DE greater than 20.
Starch hydrolysates, such as 25 to 63 DE glucose syrup and maltose syrup, have been widely used for food applications due to their availability, high tolerance, processability, and low cost. For those concerned with healthy diet applications and obesity, glucose syrup has the disadvantage of high sugar content.
Soluble dietary fiber, such as inulin, FOS, and polydextrose, has gained increased recognition as a beneficial food ingredient for the reduction of the fiber deficit prevalent in the diet of many developed countries, (e.g. United States, Europe). Dietary fiber is well known for its numerous health benefits including laxation, an increase in the faecal weight, stimulation of colonic fermentation, a reduction in blood total and/or LDL cholesterol levels, and a reduction in post-prandial blood glucose and/or insulin levels. In particular, EP 443 789 discloses the use of a pyrodextrin in a food composite for saving insulin secretion without any influence on blood glucose value. However, commercially available soluble dietary fiber suffers from the disadvantages of digestive intolerance in the form of excessive flatulence and diarrhea, low viscosity, and an undesirable taste and mouthfeel.
The term “oligosaccharide” encompasses carbohydrates that are larger than simple mono- or disaccharides but smaller than polysaccharides (greater than 9 units).
Oligosaccharides such as maltooligosaccharides, isomaltooligosaccharides (IMO) and fructooligosaccharides are gaining more attention especially in Asia markets. Oligosaccharides are purchased by food processors as an ingredient for a variety of functional foods. IMO have been produced in Asia for the past 15-20 years and are used in a variety of food applications. Most of the current use of IMO as a health food ingredients in Asian countries, like Japan, China & Korea. The use of IMO is more prevalent in Japan than any other non-digestible oligosaccharides. In 2003, IMO demand in this country was estimated 11,000 tons. IMO has been used as a sweetener in Japan for many years. IMO syrup is effectively used for traditional fermented foods in Japan.
Isomaltooligosaccharides, specifically, are glucose oligomers with α-D-(1,6)-linkages, including among others isomaltose, panose, isomaltotetraose, isomaltopentaose, nigerose, kojibiose and higher branched oligosaccharides. While human intestinal enzymes readily digest α-(1,4)-glycosidic bonds, α-D-(1,6)-linkages, particularly those linking longer polymers, are not easily hydrolyzed as they pass through the human gastrointestinal tract. That is why one of the benefits of oligosaccharides, e.g., isomaltooligosaccharides is to possess a health promotion effect, e.g. prebiotic (Kohmoto T., Fukui F., Takaku H., Machida Y., et al., Bifidobacteria Microflora, 7(2)(1988), 61-69; Kohmoto K., Tsuji K., Kaneko T. Shiota M., et al., Biosc. Biotech. Biochem., 56(6)(1992), 937-940; Kaneko T, Kohmoto T., Kikuchi H., Fukui F., et al., Nippon Nogeikagaku Kaishi, 66(8)(1992), 1211-1220, Park J-H, Jin-Young Y., Ok-Ho S., Hyun-Kyung S., et al., Kor. J. Appl. Microbiol. Biotechnol., 20(3)(1992), 237-242).
In Japan, China, Hong-Kong, Korea and Taiwan, IMO has been recognized by regulatory agencies, and this food ingredient is in market for many decades. Currently, IMO is being consumed by local populations in those countries by adding this product into a number of functional foods to exhibit health benefits, like prebiotic functions & overall improvement of digestive health.
Physiological and functional benefits of oligosaccharides include digestive tolerance, viscosity, and a desirable taste and mouthfeel. However, existing oligosaccharides have the disadvantage of relatively high sugar content, defined as the total sum of monosaccharides and disaccharides, and low detectable levels of dietary fiber, as determined by the fiber methods approved by the Association of Official Analytical Chemists. For example, commercially available isomaltooligosaccharides, e.g. IMO 500 and IMO 900 product, typically have 20-35% monosaccharides, 10 to 40% disaccharides, and less than 5% dietary fiber.
Nevertheless, IMO present also a lot of non negligible advantages. IMO syrups could replace part or all of liquid sugar syrups to produce different sweetness profiles for beverages since they are about half as sweet as sucrose. They could also be added during beer production as non-fermentable sugar syrups to replace some of the fermentable sugars altering the residual sweetness and mouthfeel of the resulting beers. Their anti-cariogenic properties could be employed by using them as replacements for sugars in many confectionary products. Dental caries are caused by insoluble glucane gums forming on the surface of teeth (plaque), and the formation of acids under this plaque which attacks the tooth enamel. The reported higher moisture retaining (water-binding) capacity which would confer improved resistance to bacterial infection could be an advantage in the baking industries in developing products with slower staling rates. However, it would appear that the major advantages and the major areas of use and interest are in the functional food area covering prebiotic products. In Japan, there are a number of so called functional foods sold which have reported health benefits, some of which use IMO as ingredients. Prebiotics are non-digestible carbohydrates that pass through the small intestine undigested and are then fermented in the colon to produce range of small chain fatty acids, specifically butyrate. It has been reported in clinical trials that IMO do not cause diarrhea when used in recommended doses. IMO are foods sources that are preferentially chosen by probiotic bacteria (live beneficial bacteria) such as bifidobacteria in the gut that reportedly help modulate the gut microflora and improve the intestinal microbial balance.
Currently, IMO is being formulated by a number of companies in United States, particularly as a source of soluble fiber and prebiotic in a range of beverages. However, in European Union., the expected use of IMO by the general population will be as a nutritive sweetener with functionality of prebiotic and fiber, mixing with a variety of other foods and beverages products for the purpose of sweetening. IMO will be used as a general food ingredient to be formulated with a range of food products manufactured by beverage industries, dairy industries and all kind sweets and dessert making industries.
Until recently carbohydrates have been classified as “simple” and “complex” based on their degree of polymerization; however, their effects on health may be better described on the basis of their physiological effects (i.e. ability to raise blood glucose), which depend both on type of constituent sugars (e.g. glucose, fructose, galactose) and the physical form of the carbohydrates. This classification is referred to as glycemic index (GI). The GI was introduced to classify carbohydrate foods according to their effect on postprandial glycemia. The GI is defined as the incremental blood glucose area after ingestion of a test product, expressed as a percentage of the corresponding area after a carbohydrate-equivalent load of a reference product (glucose or white-bread). The GI categorizes foods containing carbohydrates by their capacity of increasing glucose levels (velocity and magnitude). It is measured by comparing the increase in glucose level induced by an isolated food, under isoglucidic conditions (50 g of carbohydrates), with that induced by a chosen reference food, the most frequently used ones being a pure glucose solution. GI is defined by comparing the sum of glycemia values or the area under the curve within two hours of ingestion of the studied food with changes observed with the chosen food of reference defines. The response obtained with the reference food is given a value of 100, and all the other foods are compared to this value, expressed as percent value. GI values are grouped in three categories. High GI (≧70), intermediate (GI (56-69), and low GI (0-55). The insulinemic index (II) can be calculated from the correspondent incremental insulin areas. II is obtained under identical conditions to those for GI, simply replacing the measure of glucose with a measure of insulin. The index was introduced as a result of possible concern that blood-glucose responses might not adequately reflect the responses of the major anabolic hormone insulin, which is central to abnormal carbohydrates metabolism in type 1 diabetes mellitus.
It has now been well established that the glucose and insulin responses to different foods can vary significantly. Variations in the response can be due to a range of factors such as: type and amount of carbohydrate, protein and fat; method of food processing food form; dietary fiber etc.
It is recognized among those concerned with healthy diet applications and obesity the need for a carbohydrate inducing a lower insulinemic response and less influence on glycemic response. More particularly, there is a need for a carbohydrate with a low insulinemic response, a low level of sugars, and soluble dietary fiber with the advantages of digestive tolerance, viscosity, and a desirable taste and mouthfeel. Accordingly, it is recognized that a method of producing said carbohydrate with cost effective and industrial feasible technology is advantageous.